Automatic doors with flexible curtain typically comprise two lateral uprights, a transverse case connecting the upper ends of the lateral uprights, and a curtain movable between a closing position in which it obstructs the opening formed by the transverse uprights and the case and an opening position in which the curtain is folded or rolled into the case. Driving means, conventionally arranged in or on one of the sides of the case, allow displacement of the curtain from the closing position to the opening position and vice versa.
An important issue in the field of the automatic doors with flexible curtain concerns securing the operation of these doors in order to avoid, during displacement of the curtain from the opening position to the closing position, a collision between the curtain on the one hand and a person or a vehicle on the other hand, which may cause injury to the person or deterioration of the vehicle and/or deterioration of the curtain.
A solution known from patent FR2877684 consists of integrating into the curtain means for detecting an encounter with an obstacle in order to secure the operation of the door. The means for detecting an encounter with an obstacle are connected by a wired connection to the electronics or electromechanics for controlling the driving means of the curtain. Therefore, the triggering of the means for detecting an encounter with an obstacle allows for example, via the control electronics or electromechanics, ordering the driving means to stop the closing of the curtain and to move it in the opposite direction in order to open it.
This solution offers high reliability of detection of an obstacle and allows quite satisfactorily to preserve the physical integrity of the vehicle or of the person accidentally hit by the curtain, and the physical integrity of the curtain itself.
However, the wired connection connecting the detection means to the control electronics or electromechanics is at least partially exposed to attack from the outside environment.
This may be problematic when the door is for example exposed to bad weather and hydrometric variations, due to the increased risk of deterioration of the quality of the electrical connection. In addition, the wired connection is easily accessible; thus it risks to be sectioned, accidentally when a vehicle passes nearby or with malicious intent.
Moreover, given the speed of displacement of the curtain and the frequency of its displacements, the wired connection between the means for detecting an encounter with an obstacle and the control electronics or electromechanics is subject to a risk of premature wear, or even breakage upon a displacement of the curtain. This results in reliability problems that can be limited only by means of regular maintenance.
Then, the wired connection is limitative in terms of dimensioning of the door that it equips; it is difficult to implement as a solution to detect obstacles similar to that described in the patent FR2877684 for a door of significant dimensions, for example intended for the passage of an aircraft into or out of a hangar.
Finally, and most importantly, within the framework of applications in the fields of pharmaceuticals or food processing, the door can mark the entry or exit point of a clean room and must thus be cleaned regularly. However, cleaning the wired connection, typically a spiral wire that extends or retracts as to whether the door closes or opens, may be tedious when done by hand, or can cause premature wear of this wired connection when it is carried out by means of cleaning products which can be corrosive (after a number of cleaning operations, the spiral wire gradually loses its flexibility and could end up breaking).